The present invention relates to a fuel supply system for internal combustion engines, and more particularly, to a fuel supply system that has a pump for drawing in and discharging fuel from a tank, and a filter for catching foreign substances in the fuel.
Generally, internal combustion engines have injectors in the air intake passage. The fuel from the injectors and the air flowing through the air intake passage are mixed. Then, the mixed air is burned in the combustion chambers to produce driving power. Accordingly, internal combustion engines have a fuel supply system (fuel supplier) for the injectors.
The fuel supplier includes a fuel reservoir tank, a fuel suction pump, and a fuel supply passage from the pump to the injector, filter is usually provided in the fuel supply passage to catch foreign substances in the fuel, because the injectors can be clogged when fuel containing foreign substances is supplied to the injectors.
International Publication Number WO96/23967 describes such a fuel supplier. In the fuel supplier shown in FIGS. 4 and 5, a pump 110 and a filter 120 are assembled integrally to a lid 104 enclosing an opening 102 of a tank 100.
A lower housing 126 of the filter 120 is fixed under the lid 104. As shown in FIG. 5, the lower housing 126 is C-shaped and accommodates a filter element 124 in its internal space 123. An inset pipe 134 is integrally formed on the upper internal surface of the lower housing 126 and is connected to a discharging conduit 112 of the pump 110.
An upper space 160 and a lower space 162 are formed on the upper and lower portion of the filter element 124 in the internal space 123. The fuel discharged from the discharge conduit 112 flows into the upper space 160 through the inlet pipe 134. On the other hand, the lower space 162 is connected to a discharge duct 132 on the lid 104 by way of a duct 136.
The fuel that has flowed into the upper space 160 from the pump 110 then flows into the lower apace 162 through the filter element 124. Foreign matter in the fuel is caught by the filter element 124 The fuel in the lower space 162 is supplied to the injectors of the engine (not shown) through the ducts 136 and 132.
The pump 110 usually has an electric motor and an impeller fixed on the drive shaft of the motor (both not shown). The rotation of the impeller discharges the fuel. The pressure of the discharged fuel fluctuates continually. For this reason, when the fuel goes through the space 123, the lower housing 126 vibrates due to the pressure pulsation of the fuel. The vibration and noise are transmitted outside through the housing 126 and the lid 104.